1. Technical Field
The present disclosure relates to a method for preparing anatase-type titanium dioxide (TiO2) nanoparticles, in which nano-sized anatase-type titanium dioxide nanoparticles having excellent crystallinity can be prepared in a large amount by a simpler process.
2. Related Art
Titanium dioxide (TiO2) can be used in a wide range of applications, including photocatalysts, gas sensors and solar cells, owing to its electromagnetic, catalytic, electrochemical and photochemical properties, and many studies thereon have been conducted.
A photocatalyst refers to a substance that shows catalytic activity when irradiated with light. When the photocatalyst absorbs UV light having a wavelength of about 400 nm or less, electrons are excited from the valence band to the conduction band while positive holes are formed in the valence band. The excited electrons and holes which have strong oxidation/reduction potential react with air oxygen, water and the like to produce superoxide anions, hydroxyl radicals and the like on the surface of the photocatalyst. Particularly, because hydroxyl radicals (OH—) have high oxidation/reduction potential, they decompose NOx, SOx, volatile organic compounds (VOCs) and various stinking substances into harmless compounds, and thus can be used for the purification of air and the pretreatment of sewage and wastewater. Also, the photocatalyst has the property of killing pathogenic bacteria by oxidation and forming a strongly hydrophilic surface on which water does not form and flows down and which does not steam up. Due to these properties, the photocatalyst can be used in an infinite range of applications, including environmental cleaning, roads, house equipment, electric home appliances, automobiles, agricultural products, daily necessities, signboards, and medical supplies.
Substances known to show the above-described photocatalytic effects include ZnO, CdS, WO3, TiO2 and the like. Of these, titanium dioxide is most widely used as a photocatalyst, because it is physically and chemically stable and has excellent photocatalytic activity. Titanium dioxide is known to have three crystalline types: rutile, brookite and anatase. The anatase-type crystal is known to have the most excellent photocatalytic activity. Also, the anatase-type crystal has small particle size, and the agglomeration thereof is easily controlled. Thus, the larger the specific surface area of the anatase-type crystal, the better is the photocatalytic activity.
Anatase-type titanium dioxide nanoparticles known till now are prepared by hydrolyzing a titanium precursor to prepare amorphous titanium dioxide which is then converted to anatase-type titanium dioxide (Korean Patent Nos. 500305, 756199 and 523451).
Accordingly, it is believed that, if anatase-type titanium dioxide nanoparticles having small size and a uniform shape can be prepared in large amounts by a simpler process, they will have economic impacts on various applications, including photocatalysts.